1. Field of the Invention
The invention relates to invalid hoists of the type comprising a lifting arm projecting from an upstanding support structure or column mounted on a mobile chassis.
2. Description of the Prior Art
Hoists of the foregoing type commonly have a chassis which is open at the front between side members of the chassis with the support structure or column mounted adjacent the rear of the chassis which is supported on front and rear castors. With such an arrangement it is known for the chassis to be of adjustable width, with the side members laterally movable or pivoted adjacent the rear, to provide a minimum width for use in confined spaces and passing through doorways whereas the width of at least the front opening can be increased to fit around a wheelchair, for example.
A hoist supported on four castors provides the required manoeuvrability but suffers from lack of straight-line or directional stability, particularly when being wheeled over a deep pile carpet. To provide directional stability whilst still providing sufficient manoeuvrability it has been proposed that the chassis should be supported on two rear fixed-axis wheels and two front castors. Whilst this arrangement is satisfactory for a fixed width chassis it precludes use of prior forms of adjustable chassis.